start on reworking sys calls

lib/register/builtin/kernel.rb

@@ -17,7 +17,7 @@ module Builtin
       end
       def putstring context
         function = Virtual::CompiledMethodInfo.create_method(:Kernel , :putstring , [] )
-        return function
+        emit_syscall( function , :putstring )
         ret = Virtual::RegisterMachine.instance.write_stdout(function)
         function.set_return ret
         function
@@ -35,6 +35,39 @@ module Builtin
         function.info.return_type = Virtual::Integer
         return function
       end
+
+      private
+      def emit_syscall function , name
+        save_message( function )
+        function.info.add_code Register::Syscall.new( name )
+        restore_message(function)
+      end
+      # save the current message, as the syscall destroys all context
+      #
+      # currently HACKED into the space as a temporary varaible. As the space is a globally
+      # unique object we can retrieve it from there
+      # TODO : fix this to use global (later per thread) variable
+      def save_message(function)
+        space_tmp = Register::RegisterReference.tmp_reg
+        ind = Parfait::Space.object_space.get_layout().index_of( :syscall_message )
+        raise "index not found for :syscall_message" unless ind
+        function.info.add_code LoadConstant.new( space_tmp , Parfait::Space.object_space )
+        function.info.add_code << SetSlot.new( Virtual::Slot::MESSAGE_REGISTER , space_tmp , ind)
+      end
+      def restore_message(function)
+        # get the sys return out of the way
+        return_tmp = Register::RegisterReference.tmp_reg
+        # load the space into the base register
+        function.info.add_code RegisterTransfer.new( Virtual::Slot::MESSAGE_REGISTER , return_tmp )
+        # find the stored message
+        ind = Parfait::Space.object_space.get_layout().index_of( :syscall_message )
+        raise "index not found for #{kind}.#{kind.class}" unless ind
+        # and load it into the base RegisterMachine
+        function.info.add_code GetSlot.new( Virtual::Slot::MESSAGE_REGISTER , ind , Virtual::Slot::MESSAGE_REGISTER )
+        # and "unroll" self and frame
+        function.info.add_code GetSlot.new( slot::MESSAGE_REGISTER , Virtual::SELF_INDEX, slot::SELF_REGISTER )
+        function.info.add_code GetSlot.new( slot::MESSAGE_REGISTER , Virtual::FRAME_INDEX, slot::FRAME_REGISTER )
+      end
     end
     extend ClassMethods
   end